Learner's definition of COMMUNICATION
1 [noncount] : the act or process of using words, sounds, signs, or behaviors to express or exchange information or to express your ideas, thoughts, feelings, etc., to someone else
He is studying insect communication.
Parents need to have good communication with their children. [=they need to be able to understand and be understood by their children]
There was a breakdown in communication between members of the group.
(formal) We are in communication by e-mail. [=we are communicating with each other by e-mail]
television and other means of mass communication
2 [count], formal : a message that is given to someone: a letter, telephone call, etc.— usually singular
3 a : the ways of sending information to people by using technology
b : the study of how information is sent to people by using technology
Communications is a growing industry.
a communications satellite [=a satellite that is used to send signals for television, radio, etc., to people around the world]